This invention relates to component assemblies including simplified hardened powdered metal components.
It is known in the art that powdered metal (PM) components may be made with high dimensional accuracy which provides hardened components that require little or no further finishing. However, to reach this result without excessive cost, the component design must be producible by opposing dies with punches aligned in the direction of die motion. Thus, a hardened cam or lever, for example, may be formed with a negative cam curvature that is difficult to produce without special grinding equipment or with non round openings or slots that would require special machining processes.
In design of component assemblies such as an oscillating cam and lever or a pivoting timing lever for a variable valve timing mechanism, the ability to use hardened PM parts was desired to avoid the cost of multiple machining processes in forming the components and to provide for variations in cam shape not easily produced by grinding. However, these assemblies included components held together by threaded fasteners received in openings extending normal to the direction of required PM punch motion so that the fastener openings would have to be machined in after the forming of the components. This would require making the PM components with lower hardness which would allow subsequent machining and would require hardening which could result in dimensional distortion. A workable solution was desired.
The present invention provides a solution in modification of the PM component to provide slotted recesses that extend from a side in the direction of die punch motion through fastener receiving seats that are engaged by flanges of a second component. The recesses receive inserts installed from the side and having threaded openings that align with openings in the mating flanges to receive fasteners for holding the components of the assemblies together.
The assembly designs allow the wearing components to be made of powdered metal, which is hardened at the time of sintering, with wearing surfaces ready for use with little or no further machining. The inserts may be made by any suitable processes and machined and hardened as necessary. Where dual inserts are used, they may be provided with heads and inserted from opposite sides of the assemblies to prevent relative lateral shifting of the components after assembly.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.